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Forum Index : Electronics : Warpinverter Build
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| Alston Regular Member  Joined: 04/04/2021 Location: AustraliaPosts: 62 |
After not doing anything with my inverter since June I have got back into the final part, building and programing a controller for it. The idea behind this is that I want the startup and shutdown to be automated and also to incorporate some safety features. In this first video you can see the startup process. You press the start button- the pre-charge relay closes- the AC voltage is measured and if it's not high enough (if for some reason the inverter does start running for example) then it goes into a shutdown- if this checks out then the main contactor is closed and again if the AC voltage isn't between 230-245VAC then it doesn't close the AC output contactor. Once running it displays the voltage and current, controls the fan relay and checks for over or under voltage. Current sensing is to come but not programmed that yet. Inverter Controller An unusual safety feature I added was to incorporate a smoke sensor so if smoke is detected inside the enclosure it shuts everything down. You can adjust the sensitivity and how long it has to detect smoke for before shutting down. Smoke Detection |
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wiseguy Guru  Joined: 21/06/2018 Location: AustraliaPosts: 993 |
That all looks very good and I concur with the automation part and reasons & software decisions being made. The ac output contactor and not closing until the mains is with in a few percent of normal is the right way to do it. The smoke detector is also a nice touch, what about a spark arrestor too  Where did you get the gas detector from (that is what it looks like) ? If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 793 |
Looks like a great idea to automate the start and have an emergency stop. I hadn't thought too much about it as all the other work was overwhelming enough ... but I do like the idea. When I precharge my capacitors I don't necessarily wait for a long time before I close the main breaker. I generally watch the voltage rise to perhaps 40 volts then close the switch. The AC may have already reached 200V when I close it but it doesn't splat or seem to create any issues and the AC goes straight to 240V. I've forgotten my reasoning of why I didn't choose to use a gigavac contactor but now I'm wishing I did ... certainly to be able to force a shutdown would be handy. Does yours have a coil saver circuit where it drops the hold-in voltage after it has switched, to save power and prevent overheating of the coil? I do know I always expected to have to build some sort of overall control system for fan control, to throttle back battery charging or to switch on a mains charger (or generator) if it looks like it's not going to make it through the night. Still not sure what that will look like but hope to work out what is best once I've clocked up some kW. My output waveform looks very similar to yours with all the sprinkly vertical lines ... and using an Aerosharp filter cleans it up nicely as you've found. I've been on the lookout for a 60 amp EMI filter but they are a bit more expensive than a 20 or 30 amp one. Great job getting it going and I hope it is trouble free. Cheers, Roger |
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| Alston Regular Member Joined: 04/04/2021 Location: AustraliaPosts: 62 |
They are the MQ2 gas sensors readily available on eBay. I used the raw sensor and an LM393 to give me a digital high or low. |
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| Alston Regular Member Joined: 04/04/2021 Location: AustraliaPosts: 62 |
It would be very easy to change your layout to incorporate a Gigavac contactor and a pre charge relay. Mine does have the coil saver so draws very little current after it's pulled in. Happy to share this control PCB and code when I am done with it if you would like? I figured I would make it as a more generic inverter controller although I do plan to have a go at also generating the the bridge inverter control signals and making an all in one board for it one day. I ended up getting a 30amp EMI filter, as you say they are pretty cheap but can't say I have looked for a higher current one. |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 793 |
Yes, I have wondered about fitting one in addition to my switch, though that seems a little strange. Maybe I should just remove the switch altogether. Do you have any details as to the model or part number of your contactor ... I like the idea of it having an inbuilt coil saver. I have often wondered about using a micro controller to run the whole machine ... but I'm not confident enough to risk trying to design something myself and add a new potential problem ... so my idea is to prove it all first for a substantial amount of time, and then look into it. If I recall correctly, Tony said he's just clocked up six years with his control board, so there's no doubt that it can work. I'm not gonna tempt fate. I have done some assembly language programming back in the 8080 and Z80 days and some PIC processor work ... and a small amount with Arduinos ... but I do like the idea of a simple dedicated control board ... and a seperate overall system control. Will be interesting to see how well your new filter works. I noticed with the short trial with the Aerosharp one, that it cleaned up my waveform ... but the higher load I applied, it started showing up again. Cheers, Roger |
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| Alston Regular Member Joined: 04/04/2021 Location: AustraliaPosts: 62 |
This is the contactor I used Roger https://www.ebay.com.au/itm/284658500316 The Arduino or Raspberry Pi Pico is the way to go. With the Pico you can program in C, MicroPython or Arduino (C++). For this kind of thing using Micropython is the easiest as timing/resources are not really an issue to worry about. |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 793 |
Thank Alston, I may just get one of them. I have a 12 volt supply once my control circuitry is turned on ... and I could run it in series with my cct breaker. It's a 300 amp breaker, so that would still provide overload protection ... but do any other switching or emergency cutout using the solenoid. The breaker is horribly large but is an integral part of the power-in circuit now ... with a 20mm by 5mm copper bar from output to the main busbars. Looks like I'll need to start studying some higher level languages too. I do have a few arduinos and a couple Raspberry Pi's here, but have done little with them ... though as mentioned earlier, I have no intention of replacing Tony's control board any time soon. No point risking hiccups unnecessarily. I mentioned that I thought having fitted the 5 or 6mm spacer between the core and the secondary winding had been a pointless exercise ... but Tony has since suggested that it quite likely has reduced the capacitive coupling between them both. He has also suggested I try an electrostatic shield between the primary and secondary to reduce the vertical switching spikes on my output waveform ... so I will try that first. I have a heap of the shielding strap that came out of the Aerosharp toroids I unwound, so that part's relatively easy. Another option would be to fit a spacer between secondary and primary ... but of course that would require lengthening the primary winding ... and more difficult, cutting away at the angle iron above it to create enough room for the thicker tx. Cheers, Roger |
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Murphy's friend Guru Joined: 04/10/2019 Location: AustraliaPosts: 581 |
Roger, all 4 of my warp toroids have that static shield, it did nothing to prevent mosfet mishaps  .I did not use the ribbon type as recycled from aerosharp toroids, but glue backed copper foil instead. You can see how in my old warpinverter thread under the 'tinker' author if you want to try that method. |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 793 |
Thanks Klaus, I do recall reading of someone doing it ... and makes sense that it was you. At least I know where to look now, thank you. In communicating with Tony, he pointed out that the Aerosharp method is not a good idea because if I were to wind on a heap of turns, then earth the centre winding ... in his words, "both ends of the screen may have pretty high induced spike voltages" ... which makes sense. ... and "The best electrostatic screen will only use one turn so there is very little voltage induced between the ends of the screen." I'll look your method up shortly, but now I understand why you didn't use the Aerosharp foil. I do have some of that adhesive copper foil, but nowhere near enough to cover the big toroid. I'm hoping the electrostatic screen might help reduce some of the switching interference ... the sparkly/dancing vertical spikes I see on the output waveform. The EMI filter I tried certainly remove them under no load ... but it is worth trying to see if I can get rid of them at the source. Cheers, Roger |
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| wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 993 |
Roger, at the bottom of page 47 of this thread here is another shielded toroid Thought I remembered Mark doing this too. If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 793 |
Thanks Mike, I don't recall seeing that before. Certainly an interesting way of doing it. Not sure my welding skills are up to joining that stuff, though I could try ... and I reckon I have some of that flashing in the shed already. I checked out your thread too Klaus, and I did wonder how well that adhesive copper foil joins electrically to an adjoining piece, with the adhesive in between. I find when I use the stuff to repair a burnt or corroded board, that I end up soldering at the edge occasionally just to make sure it's connecting somewhere. Cheers, Roger |
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| Murphy's friend Guru Joined: 04/10/2019 Location: AustraliaPosts: 581 |
Yes, it's no big deal to either check the electrical continuity with a meter between the foil sections or add a solder join for peace of mind. You have to solder on the earth wire anyway. Just make VERY sure you do not create a short turn. To check that, measure the magnetising current before the foil application and after it. It should be the same. I remember placing an experimental wire short turn and the magnetising current increased by a very noticeable amount. I got the copper foil from Ebay. You want a wide section around the outside and a much narrower one to go thru the hole to avoid many overlaps. |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 793 |
Thanks Klaus, and yes that has been in the back of my mind all the way through, how to avoid a shorted turn. I reckon I have it in my mind how to do it now and I've ordered a few lengths off ebay, so just need to wait. Electrician turned up yesterday with 40+ metres of 16mm "extension cord" to run from the inverter to the switchboard ... so it's all happening now. He kinda hinted I could run out the cable through the conduit etc ... so I have a job for the weekend while I wait for the copper foil. Cheers, Roger |
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